Monday, July 1, 2013

Chemistry of hojicha aroma


TV can’t deliver the smell to the viewers.  A TV program on NHK was trying to explore the aroma of hojicha, roasted green tea.  They had a sommelier that is an expert on distinguishing flavors and describing them with words.  That’s a smart idea!  For producing hojicha, the green tea was roasted four times.  He smelled the tea after each process, and described the odor that he found in the tea by comparing it to some other materials.
1st smelling: green grass, lime
2nd smelling: rock salt, salty water
3rd semlling: roasted hazelnut, chocolate,
4th smelling: Sweet vanilla beans, coffee, cigar,

I sincerely admire the ability of the sommelier.  He also compared the aroma as small white flower and big yellow flower.  I can’t even imagine the difference of them, hahaha.  I wish that I had the fine sense of smell and the expressive vocabulary.  The aroma of hojicha is created with various flavors.  It seems complicated and profound.

At the early roasting steps, the sommelier found the aromas like the items shown on the left side of this picture, and for the 4th smelling, he finally found the aroma like the items on the right side.
Top column from left to right: green grass, small white flower, hazelnut, big yellow flower/ coffee, soy sauce, maturing aroma of cask,
Bottom column from left: lime, mint, rock salt, chocolate, orange/ vanilla beans, cigar, cinnamon


Tea has more than 300 kinds of the smell substances in it.  However, most of them are attached to sugar in the leaf and they are sealed.  By slowly roasting green tea in the first three steps, those aromas will separate from the sugar and get freed.  In the final step with the strongest roast process, the sugar will merge with amino acids and create the roasted aroma, which is called the amino-carbonyl reaction.  The odor of Hojicha consists of a combination of the latent aromas of tea and the roasted aroma that is created by heating.  Tea potentially has the hidden aromas but you can’t truly enjoy them with green tea (sencha).

In the TV program, they didn’t tell which substance of the hojicha aromas has the ability to get people relaxed.  Now, I wonder if Chinese or black teas have the same effects, which usually have richer aromas than the Japanese green teas.  Anyway, it is for sure that hojicha has a great efficacy to make people relax and happy with its alluring fragrance.  In the feature post, I’ll introduce how to roast hojicha.

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